[S390] cio: Use path verification for last path gone after vary off.

If the last path to a device is gone after a chpid has been varied
off, putting it on the slow queue doesn't prevent a device driver
from still attempting to use it (it may stay on the slow queue for a
long time). Instead, trigger a verify event which will prevent I/O
attempts from the device driver immediately.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/cio/device_fsm.c b/drivers/s390/cio/device_fsm.c
index de3d085..7665000 100644
--- a/drivers/s390/cio/device_fsm.c
+++ b/drivers/s390/cio/device_fsm.c
@@ -59,6 +59,17 @@
 	cdev->private->state = DEV_STATE_DISCONNECTED;
 }
 
+int device_trigger_verify(struct subchannel *sch)
+{
+	struct ccw_device *cdev;
+
+	cdev = sch->dev.driver_data;
+	if (!cdev || !cdev->online)
+		return -EINVAL;
+	dev_fsm_event(cdev, DEV_EVENT_VERIFY);
+	return 0;
+}
+
 /*
  * Timeout function. It just triggers a DEV_EVENT_TIMEOUT.
  */